1. Field of the Invention
This invention relates to a ratchet assembly, more particularly to an easily direction-convertible ratchet assembly for a hand tool.
2. Description of the Related Art
An example of conventional ratchet screwdrivers has been disclosed in U.S. Pat. No. 5,379,873 and comprises an elongated housing which has an axially extending cavity that receives a drive shaft with a ratchet wheel, and an axially extending peripheral slot that is confined by two opposing vertical walls. The housing is further formed with a horizontal bridge surface and an inclined support face so as to support two ratchet pawls when two finger portions of the ratchet pawls engage the ratchet wheel. However, only the finger portions engage the ratchet wheel to transmit the torque force of the housing to the drive shaft, thereby resulting in a limited torsional force transmission capability.
Another example of the conventional ratchet screwdriver includes a mounting body, two spring-biased ratchet pawls which are received in the mounting body, and a rotating shaft which has a front end adapted to engage a screwdriver and a rear annular end with an internally toothed portion that is sleeved on the mounting body to engage one of the ratchet pawls. An adjusting ring is sleeved on the mounting body adjacent to the ratchet pawls to depress or release the ratchet pawls so as to convert the rotating directions of the mounting body for transmission to the rotating shaft. It is inconvenient to operate the aforesaid ratchet screwdriver since the user requires both hands to rotate the adjusting ring and the mounting body. In addition, the size of the ratchet screwdriver is increased due to inclusion of the adjusting ring.
The object of the present invention is to provide an easily direction-convertible ratchet assembly that is capable of overcoming the aforementioned drawbacks.
According to this invention, the ratchet assembly includes a mounting body, a rotating shaft, a ratchet wheel, right and left pawl members, an actuator, and a biasing member. The mounting body includes front and rear portions opposite to each other in a longitudinal direction, and an intermediate portion interposed therebetween. The rear portion is adapted to be secured to and is rotatable with a handle when the handle is turned by a torque force. The front portion includes a front end wall which extends in a first plane facing toward the longitudinal direction, and has an inner tubular hole which extends rearwards into the intermediate portion so as to form an inner surrounding wall surface that surrounds a rotating axis parallel to the longitudinal direction. The inner surrounding wall surface has upper and lower areas opposite to each other in a first transverse direction transverse to the longitudinal direction. The inner tubular hole is divided by a central plane, which passes through the rotating axis and which is parallel to both the longitudinal direction and the first transverse direction, into right and left chambers. The rotating shaft is adapted to be rotated with a drive shaft about the rotating axis, and includes proximate and distal portions relative to the drive shaft. The distal portion is inserted in the inner tubular hole along the rotating axis. The ratchet wheel is mounted on the distal portion so as to be rotated about the rotating axis, and includes right and left half tooth portions which are respectively located in the right and left chambers. The right and left pawl members are respectively disposed in the right and left chambers. Each of the right and left pawl members includes a pushed stem which has an actuated end that movably extends upwardly and into the upper area and outwardly of the intermediate portion, and a coupling end that extends downwardly from the actuated end in the first transverse direction, and a pawl body which is disposed on the coupling end, and which includes a pawl engaging surface that is disposed to face upwards and in the first transverse direction and that is movable toward and away from a respective one of the right and left tooth portions, thereby engaging and disengaging the same, and an abutting surface opposite to the pawl engaging surface in the first transverse direction. The actuator is mounted on and is shiftable relative to the mounting body between normal and reverse positions. In the normal position, the actuator releases one of the actuated ends of the right and left pawl members to permit the respective pawl engaging surface to move upwards so as to engage a respective one of the right and left tooth portions, thereby transmitting the torque force from the rear portion to the respective one of the right and left tooth portions so as to turn the rotating shaft in a clockwise direction, while the actuator depresses the other actuated end to move the respective pawl engaging surface to disengage the other one of the right and left tooth portions so as not to interfere with the transmission of the torque force. In the reverse position, the actuator releases the other actuated end to permit the respective pawl engaging surface to move upwards so as to engage the other one of the right and left tooth portions, thereby transmitting the torque force from the rear portion to the other one of the right and left tooth portions so as to turn the rotating shaft in a counterclockwise direction. The biasing member is disposed to bias the abutting surfaces to move the pushed stems against the depressing force of the actuator.